IPA: /ˌʌn.sɪm.pəˈθɛt.ɪk/
KK: /ʌnˌsɪmpəˈθɛtɪk/
Not showing kindness or understanding towards someone else's feelings or problems.
His unsympathetic response made her feel even worse about the situation.
Unsympathetic → It is formed from "un-" (meaning not) and "sympathetic" (from Greek "sympatheia", meaning fellow feeling or compassion). The word "unsympathetic" means not having or showing compassion or understanding for others' feelings.
Think of 'not' ('un-') having 'fellow feeling' ('sympatheia') — that's why unsympathetic means lacking compassion.